1. Field of the Invention
The invention relates to electric toothbrushes.
2. Description of Prior Art
Electric toothbrushes are well-known and generally comprise a handle incorporating a motor and a shank that fits to the housing and has a brush head at its remote end. The motor is arranged to move bristles held in the brush head to cause the bristles to rotate or vibrate in some cases by vibrating the shank relative to the housing. In this way a more efficient brushing and cleaning action is achieved than simply manually moving the bristles over the surfaces of teeth and gums.
Electrical toothbrushes also have switches to turn the motor ON and OFF and in some case to enable different motor speeds to be selected. Normally, the present day toothbrushes have compartments for a battery, which may be a re-chargeable battery. The brush head may detachable from the shank, for cleaning or replacement. These are all features well-known in the art and so will not be further described in the specification. The present invention is more particularly concerned with the manner of driving a brush head, which so far is often complex, and/or comparatively expensive to make, and/or prone to failure.
It is an object of the invention to overcome or at least reduce these problems.
According to the invention there is provided an electric toothbrush comprising a housing incorporating an electric motor having a drive shaft that rotates about a longitudinal axis of the housing, a shank extending beyond one end of the housing generally in line with the longitudinal axis that supports a brush head at its remote end, in which the shank is pivotably supported intermediate its length adjacent the one end of the housing, and including a mechanical coupling between the drive shaft and a near end of the shank arranged to cause both the near end and the brush head to move through a circular path as the drive shaft rotates.
The mechanical coupling may comprise an eccentric cam mounted to one of the drive shaft and the near end of the shank and a cup that fits over and engages sides of the cam on the other of the drive shaft and the near end of the shank.
The eccentric cam may have a peripheral continuous channel that extends axially with respect to the longitudinal axis and the cup has a finger that engages in the channel so that when the drive shaft rotates the cup (and the shank) is urged backwards and forwards along the longitudinal axis.
The shank may be held to pivot by the sides of an aperture formed in a wall of one end of the housing.
A resilient sealing member may be included that fits around the shank and to the said wall.
The general xe2x80x9ctoothbrush arrangementxe2x80x9d may also be used for skin care products such as brushes or rubbing pads.